Air hammer



S. YABE AIR HAMMER July 25, 1939.

Filed March 15, 1937 I V/ifig;

Patented July 25, 1939 UNITED STATEfi PATENT oFFlss Claims.

This invention relates to an air hammer.

In the air or pneumatic hammer hitherto known in which the piston in the compressing cylinder is reciprocated by the crank shaft revolved at the same speed during its whole stroke, the speed of the piston is contrarily retarded at the end of the up stroke when the highest compression is to be required, which results in the weakening of the hammering power. In the present invention these difliculties are completely removed by the rapid movement of the piston at the end of its up stroke, the hammering power being highly increased immediately before and after the hammering. The further advantage In order that the invention may be clearly un-' derstood and readily carried into effect it will now be described by way of example with reference to the accompanying drawing, in which Figure 1 is a side elevation of the air hammer partly in section,

Figure 2 is a front section of part of same,

Figures 3 and 4 being rough sketches showing the manner of working.

In the air compressing cylinder l, the piston Zis reciprocated and the air compressed is introduced into the hammering cylinder 3, so that the hammering rod 4 is moved up and down. In order to rapidly reciprocate the piston 2 at the end of its up stroke the elliptic toothed wheel I is keyed to the crank shaft 6 connected. to the piston rod 5, said elliptic toothed wheel I being engaged with another elliptic toothed wheel l3 which has same major and minor axes keyed together with the flywheel l2 to the auxiliary shaft II revolved through the toothed wheels 9, III by the motor 8. The engagement of the elliptic toothed wheels 1 and I3 is made in such a manner that the minor-axial part of the for- 5 mer is in mesh with the major-axial part of the latter, when the piston is at the end of its up stroke. 7

In the present invention the speed of revolution of the crank shaft 6 is accelerated or re- 5 tarded according as the major-axial part of the eccentric wheel I3 is in mesh with the minoraxial part of the eccentric I or the minor-axial part of the former engages with the major-axial part of the latter, when the auxiliary shaft H is revolved with a given speed by the motor. Consequently, the speed of the piston reciprocating through the piston rod 5 by the revolution of the crank shaft is gradually accelerated in its up stroke, while-it is gradually retarded in its down stroke. It is to be noted that the 1 greatest power is required for hammering immediately before the hammering rod comes into contact with theanvil or when the piston in the compressing cylinder approaches the end of its up stroke. By rapidly reciprocating the piston 15 near the end of the up stroke the air is highly compressed and the speed of the hammering rod largely accelerated, the hammering power being thus considerably increased. On the contrary, the speed of said rod is gradually retarded, when l0 moved upwards. Immediately after the hammering, the rod quickly moves upwards so that the time of contact with the material to be forged is reduced to a minimum and cooling of the latter may be avoided completely.

What I claim is:

1. In a pneumatic hammer, the combination with a reciprocating hammer, a reciprocating pump and conduits cooperatively connecting the pump and hammer, of a power drive for said 30 pump comprising, a driven shaft operatively connected thereto, a uniformly rotating driving shaft, a variable gear connection between said shafts, said gear connection causing said driven shaft to be driven at an increasing speed from 35 the driving shaft through the upper portion of thestroke of the pump to increase the impact of the hammer upon the work.

2. In a pneumatic hammer, the combination with a reciprocating hammer, a reciprocating 40 pump and conduits cooperatively connecting the pump and hammer, of a power drive for said pump comprising, a driven shaft operatively connected thereto, a uniformly rotating driving shaft, a gear connection comprising a variable radius gear on the driven shaft, and a variable radius gear on the driving shaft adapted to mesh with the variable radius gear on the driven shaft, said gear connection causing said driven shaft to be driven at an'increasing speed from the driving shaft through the upper portion of the stroke to increase the impact of the hammer upon the work.

3. In a pneumatic hammer, the combination with a. reciprocating hammer, a reciprocating pump and conduits cooperatively connecting the pump and hammer, of a power drive for said pump comprising, a driven shaft operatively connected to said pump, a uniformly rotating driving shaft, a gear connection comprising a spur gear fixed eccentric to the driven shaft and a spur gear fixed eccentric to the driving shaft and in mesh with said first gear, said gear connection causing said driven shaft to be driven at an increasing speed from the driving shaft through the upper portion of the stroke of the pump to increase the impact of the hammer upon the work.

4. In a pneumatic hammer, the combination with a reciprocating hammer, a reciprocating pump and conduits cooperatively connecting the pump and hammer, of a power drive for said pump comprising, a driven shaft operatively connected to said pump, a uniformly rotating driving shaft, a gear connection between said shafts comprising, intermeshing gears having major and minor axial portions, said minor portion of the gear on the driven shaft being engageable With the major portion of the driving gear to cause said driven shaft to be driven at an increasing speed by the driving shaft through the upper portion of the stroke of the pump to increase the impact of the hammer upon the work. 5. In a pneumatic hammer, the combination with a reciprocating hammer, a reciprocating pump and conduits cooperatively connecting the pump and hammer, of a power drive for said pump comprising, a driven shaft operatively connected to said pump, a uniformly rotating driving shaft, a gear connection between said shafts comprising equal elliptic toothed wheels having major and minor axial portions, said minor portion of the Wheel on the driven shaft being engageable with major portion of the driving wheel to cause said driven shaft to bedriven at an increasing speed by the driving shaft through the upper portion of the stroke of the pump to increase the impact of the hammer upon the work.

SHIGERU YABE. 

